Basic terms of electricity, expalanations of basic
vocabulary or terms of electric.
The artiscle has 2 titles because
neither basics of electric nor the vocabulary of electric does not Express what
ı meant that well.
While explaining the article
mostly ı had to explain the basic rules or ideas too. However the article is
not written for the explanation of the principles. Therefore ı had to use a
double title.
This
article aims to explain the everyday used terms and what to know to understand
electric.
Voltage (potential-volt):
The force to push (or pull) the
electrons between the poles of the source may be the explanation of voltage.
Also the difference of potential energy between the poles that can be released
from either end is another explanation. However both of these explanations mean
nothing for an end user. So it would be better to explain with an analogy.
Voltage (or the potential difference) indicates how hard electrons are pushed
from negative pole to positive pole in DC. (and from live pole to neutral pole
in AC). The unit is volt and shown by the letter V. Even though it will piss
the engineers and physics professionals but voltage is like the speed of the
electricity. As 100 km/h (or 60 mph) tells you just how fast it is not what
kind of car it is voltage like 100 or 1000 or else tells you the potential of
the electricity not how much electric inside.
Current (ampere):
Unlike
volt current tells us more about the amount of electric used or flowing in the
circuit. Amount of ampere is directly related with the number of electrons
flowing in the systen (circuit). Counting the number of electrons in the system
is mostly impossible to count and at the same time has not much practical
importance. Same amount of electrons can do different amount of work (or carry
different amount of energy). Just one electron can have 200 volts or billions
billions of electrons can do so. Because of that instead of counting the number
of electrons measuring the current and doing calculations with ampere and volt
would tell you much abuot what is going on inside.
As
another example to piss the engineers: lets think of a water transferring
system. The pump is the source of electric and electric is the water inside the
pumps. You need tor inse something with the water pumped.
The
speed of the water is volts. And the amount of water is ampere. The pressure
which is related with both the voltage and the ampere is the real amount of
work to be done. You can get the same amount of pressure with higher pump speed
and less amount of water. The opposite is true also. More amount of water and
less pumping speed can give you the same pressure measure.
Additionally
the amount of water is related to how many water molecules there are in the
system but till now we did not need to count how many water molecules we had or
used.
The
sign of the current is A but in most circuit diagrams current is shown with the
letter I. A is for amounts in calculation. It tells us the amount but not the
direction. I is for showing the direction in a diagram and does not Show how
big is the current. This is fort he different usages in different branches. An
end user mostly sees the value ending with A through out its life.
Work (Watt):
This
term shows us the total thing done by the electric in the system. This is like
the pressure in the example above. Watt is not only related with the amount of
electricity as current. It is the amount calculated both current and voltage.
The sum of both values give us work to be done as watt.
As another example: we have a
group of uniqe balls which are 10 grams each. We have to move a rock weighing a tonne by throwing these balls.
This
rock can be moved by throwing many balls with a considerable speed (like
flowing water can demolish buildings). Yet same motion of rock can happen with
less balls with higher speeds (a bullet can do alot because of its speed.)
As
another example the crancing motor of a standart car is about 2000 watts. The
2000 watt engine in a vacuum cleaner has the same power with the 2000w cranking
engine. However the one in the vacuum cleaner Works with Wall outlet and in a
220volt grid it uses less than 10 amps. A cable of 1 mm2 is enough to carry
that current. Although in the car engine 12 volt system is used and a current
more than 150 amps is used fot the same watt. A cable of 20 mm2 is needed for
that kind of current.
The
amount of electric used by a system or a device is measured by work done as
watt. Mostly Word of electrical energy is used in Daily terminology which is a
wrong term scientifically. İt is impossible to measure the energy directly. As
told before electricity itself is not an energy form. Electricity only carries
energy. So just measuring the amount of electric is not a good way to bill
people. However it is so easy to measure or calculate the amount of work that
can be done by the energy carried by the electric. So power grid bills people
by measuring watt.
If you
want to compare the power consumptions of two or more devices read their values
ending with W or Watt. Bigger value usesw more. Neither volt nor ampere gives a
true measurement alone.
VA value:
This is
also the sum of multiplication of volts and amps. However unlike watt it does
not give us how much work is or will be done. The VA is a calculated value to
Show the total amount of electricity to flow in a system containing voltage and
current changes. Systems like UPSs voltage stepping up or stepping down occurs
and the total capacity of work to be done is scrictly correlated to the circuit
capacity. The VA is calculated theoretically by using the values of the
electronical parts. So the VA value is mostlu used to Express the empedance,
resistivity, theoretical capacity; not the work to be done.
As a conclusion the VA value is
almost never equal to watt. VA is a calculated theoretical value which does not
contain practical efficiency and resitances in the circuits and valid in an
imaginary universe. However watt is a measured value valid in real universe.
As a marketing strategy in some
devices like UPSs VA value is written in much bigger fonts or given only; since
it has always a bigger value than watt and that makes buyers think that the
device is more powerful than it is in real.
An UPS shown as 1000VA can be
300w or 700w or 500 w in real. If an efficiency value is given the
multiplication sum of VA and that efficiency value is the actual watt of the
device. If no efficiency is given mostly it is about %50 efficient. For example
if you have a 1000VA UPS without an efficiency it is possible that the
effective power value is around 500 w.
Starting current:
I have looked a lot of
dictionaries and it was nearly a mess of words. In French the term is demerage
and in most languages it is something similar to that. However in english there
were alot of translations which most seemed not suitable. Demmurage, initiating
current, inrush current were some of the ones ı could find. The most suitable
one was starting current so ı choosed it. If anyone knows a better Word please
let me learn.
After all: Starting current is
mostly used in electric motors. However this happens in almost all electric and
electronic systems. Practically it is meaningless for most kinds of circuits.
When an electrical or
electronical system starts working, the system uses more than the domestic
current/normal current to be used. This is valid for all kinds of electric
currents however in most of the systems this value is so small that it is
mostly ignored. For electric motors this value is considerably high. Because of
that this term is more likely to be known as valid for electric motors.
As an example starting current
for a led lamp system is no more than %0,01 and the initiating time is less
than a milisecond. Though for an universal type electric motor the starting
current is about 10 times of the usual current and the initaiting time is a lot
longer. The dimming of the lights when a high power non invertor air condition
starts is because of that.
The motor system of the air
condition needs 7-8 times more of the usual current. Wall outlet would be
insufficient for a while because either the system with less internal
resistance (here the motor system) would take more current on or the wiring
system would be insufficient to compansate the current rise in such a short
time. In some old houses when a vacuum cleaner starts to work lights go dim until
the motor of the cleaner returns to use its usual current. The wiring can not
compansate the excess current need.
When using the Wall outlet
starting current is not a very big problem but in a mobile system like
generator, battery, UPS; power to be provided is mostly limited so the
calculation must be made considering the starting current.
Resistance:
Resistance is the name of a
circuit element in electronics. Also the name of a term that we will meet
everywhere. As the term resistance is the defence of neither the total system
nor an individual element itself (like bulb, battery, wire…etc). In another way
resistance is the friction of electricity while passing through. Every matter
has its own resistance against electricity. For examle porcelain has a very
great resistance that practically does not allow electric to flow over.
Carbonised silicon has a medial resistance enough to block electric partially.
However most metals have small resistance enough to allow currency flow over.
Even metals have internal resistance so not every metal is used to transport
electric. Cupper and aluminum are the most common ones uses since they have
much less internal resistivity than most of the metals and are more affordable
than gold, silver or platinum.
In all electric circuits the
electric given from one end is never equal to the electric taken from the other
end. This is the lost energy because of the resistance inside the system. Even
the wires with the least resistance has a resistance and there is loss.
Like the wires the circuit
elements like motors, lamps, electronic parts even the batteries cause energy
loss because of their internal resistances apart from the energy consumed
because of the work done. As an example a lamp of 100 watt consumes electricity
more than 100w because of the internal resistance of the system apart from the
lighting work of the lamp. If you limit the electric energy just consume; as
100w you will get less light than the
unlimited version.
This is why a circuit always
consumes more than the calculated energy. Lost energy because of the
resistances efficiency is never %100.
Electric currency always prefer
to flow through the least resistant way. Because of that systems with less
internal resistance get more of the electricity when had to share the currency
with another circuit system. The dimming of the lights when an electric motor
starts to work is because of this phenomenia.
As told before electric sources
have internal resistances too. Wall outlet systems have just one source so the
problem is negligible but in a battery operated system a cell considers the
other cell or cells like circuit elements and try to flow current over them. If
the internal resistances of the batteries are equal only a loss caused by the
internal resistance of the battery happens and the circuit element phenomenia
is then negligible. However if the internal resistances of the cells are different
this phenomenia becomes considerable and every cell tries to charge the other.
As a result a cell provides current both for the circuit and the charging
process of the others. This make the battery come to end much before the
calculated or expected time. Also in lithium used systems this may cause the
batteries get warm and explode. This is why it is always written on electrical
and electronical devices not to use different types of batteries and differend
aged batteries together.
For example if you use alcaline
and zinc carbon battery together to work a toy or something else like that; the
alcaline battery which has higher resistance and more current to be provided,
will try to charge the zinc battery. Since zinc battery does not have a rechargeable
architecture it will leak. Also the alcaline battery will loose too much power
while providing the current needed and it will get warmer and warmer during the
process. It may also leak. If a lithium ion battery was used beeing warmer
would push the lithium battery into an unstable state. Beeing unstable of
lithium batteries is dangerous because they mostly contain organic solvents
which are highly flammable. Leaking of this solvent in a heated system may
always explode. This explosion is not a metaphor; a real explosion may occur.
Wires also have internal
resistances. Because of that using wires with suitable thickness will help you
to prevent losses caused by internal resistance. Think of a narrow road with
crowded traffic. Going from a place to another from that kind of a road is like
a torture. Also even though you go slower more gas is burned in such a road.
That phenomenia happens in a narrow wire.
Also wire with less thickness will heat more
than a suitable one and the heating of the wire will also cause more loss of
energy. Like the analogy above a road
with a crowded traffic is hotter than the perimeter. This also effects the
consumption. By the way practically no car burns because of the high temp on
the road but a wire can start to burn if you try to pass bigger energies
through an inadequate wiring. The wiring will pass the most capacity available
but the system will still be hungry to energy. So that wiring has to work
overcapacity for a long time and heat produced because of that may cause the
plastic coating catch fire.
Direct current:
Electric flow through a system
may be in different forms. This depends on the circuit architecture and the
electric source. Even though the flowing materials are the electrons the difference
in the character of the flow changes almost everything.
In direct current electrons flow
from (-) pole to (+) pole. Two wires are needed. One for (-) pole and one for
(+) pole. This makes establishig power grids with direct current much more
expensive. Also the 3D movement of direct current is only in one phase,
dividing the current is impossible so the wiring has to do all the duty which
brings us the point of thicker wires.
Direct current is mostly produced
by batteries; the chemical electric sources or another types of currents may be
changed to direct current by circuit elements like diodes.
If the electrones in a system
flows uniformly only in one direction; then we can speak about direct current. Electrons flow through
the wiring while pushing the available electrons of the metal in the wire.
Since electrons have to move all through the system energy loss and heating
occurs more in this current. In another way direnc current in domestic voltages
(voltages in battery operated systems or even the wall outlet voltage can be
considered as domestic voltage) is a less efficient way of using electricity.
As an analogy; a scene in western
films would be helpful. When a fire occurs two lines of people are formed. One
line carries filled water buckets from the water source to the fire. The other
line carries empty buckets from the fire place to the water source. The flow
character of electrons in direct current is like that. Electrons go from one
line than return from the other.
A thicker wiring will be needed
to flow a direct current than to do it with the same amount in alternating
current. As an example 6 mm² thick copper wire is enough to carry 100 amps of
electricity in alternating current. Although in direct current 20 mm² would be
much safer for direct current. Of course the length of the wire is also another
factor to be considered but the wire to carry 200 amps of electricity in a city
power grid is almost equal to the jumper wire of your car which is much shorter
and uses the same current.
Because of these carrying
electricity to longer distances with domestic voltages in direct current is
almost impractical. Thomas Edison who most of the people think him as the
father of electric (which is not quite true) used direct current for the power
grid he built. He had to use a regulator in every section of 2 kilometers
(about 1.2 miles).
The disadvantages of edison’s
direct current against tesla’s alternating current were so obvious that Edison
could not prove that his direct current is beter. Instead he tried to troll the
alternative current. Electric chair to execute people was discovered during
this trolling. (electric chair stil works better with direct current.
At the end alternating current
usage became much superior to direct current in power grid.
However the basics of electronics
was established during the times where the general power grid was not so common
and most of the electric need was provided by the batteries; electronic is
based on direct current. Also all kinds of batteries give out direct current;
which are inevitable. When addition of how easy to change alternating current
to direct current; the direct current is as inevitable as alternating current
in our world despite the disadvantages.
Alternating current:
This type of current is not
caused directly by the movement of electrons. Alternating current is formed by
the electrons pushing the electrons after it. Then the pushed one does the same
to the one next to it. Then it does to the next one. And so and so. Then this
happens in the opposing direction. The pusher electrons go back to their
original place and they push the electrons there.
If we use the fire fighting scene
in western films; this time buckets are not given from one hand to another.
Every one pours the water in its bucket to the next one’s bucket. So buckets do
not move. You can say that in alternating current there are two wires also.
That is true. But the second wire is not for permanent electric flow. It is
called the neutral wire which is used to collect the pushed electrons until the
process is backwards.
Because of that reality electrons
move less. Therefore there is less friction. So it is much possible to
transport energy with a considerably higher efficiency. Depending on the wiring
and weather conditions efficiency is between %80-95 for 1000 kms (about 600
miles)which is much more effective than dc current. Also thinner wiring than dc
current is enough for equal current transport. If dc was used instead of ac in
todays power grid system, probably world’s copper reserved would come to an end
these days.
Since the electrons do not move
actually; in order to transfer electrical energy on eline per phase is enough.
As alternating current consists of electron push and pull action temporarily;
there is a relative and temporary electrification at the end of the live wire
and only using a neutral (or dead) wire is used. This is why only one of the
wires in our wall outlets at home is alive (has current) and the other one is
dead (neutral).
In long distance high voltage
grid there is no neutral wire. Only live wirings are enough to carry electric
for any distance. Grounding the alternator while generating the electric and
the regulator system installed is enough to compansate the neutral wire need.
Because of that 3 live wires is enough for a triphased power grid. No need for
3 more neutral wiring. If it was dc every
phase would need 2 wires.
In some high voltage grids 4, 5
or more wiring could be seen. The excess wires are mostly for lightning
protection. Also sometimes the current to be carried is so much that the wire
that has enough thickness would be impractical. So the current would be divided
into separate wires. Because of that power lines with 4, 5, 8 and more
indivisible with 3 numbers can be seen.
It is normal to ask a question
like “if one live wire can carry electric and a simple grounding is enough why
there are 2 wires at home wall outlets. If every house or building made its own
grounding instead of a common city wide dead wiring; under heavy rain or flood
the pedestrians would be affected by electric current. İn order to prevent that
city or section wide grounding is done in a safe place and the dead wire
derived from that grounding is used at homes.
Neutral wiring is practically a
grounding. In some countries some brilliant (!) technicians use dead wire to
ground the line. Or some dear awesome intelligent (!) ones use a metalic system
like waterpipes for dead line. This is a secureless and useless progress.
Even its name is neutral as we
have heard before in ac current there is a temporary electrification in neutral
pole. This means neutral wire is not always neutral; it is frequently charged.
Not as much as the live wire but enough to affect the user. Because of that the
wiring to protect you from electric will be charged if any of the brilliant(!)
ideas mentioned above are done. The installation to protect you can burn you.
Direct current is lineer. This makes
direct current individable since lines are only one dimentioned. It does not
matter whether the line is upwards or downwards or right or left. Line is
always a line. This explanation does not mean much for anyone who is not
engineer. It may be more understandable while explaining ac.
Alternating current is planar.
Unlike lines planes are three dimentioned in our universe. A horizontally
placed plane is never same as avertivcally placed plane. One has length and
width other one has width and depth; another has length and depth. This makes
triphase current that allows us to divide amountof current into three. As an
example carrying 150 amps in a single wire is both risky and impractical since
transfer loss will be a lot. However dividing it into three and transporting
150 amps in 3 wires with 50 amps each is much more secure and effective.
Because of all these advantages
alternating current of tesla whom we do not know well won the war of currents
instead of edison’s direct current whom most of us know him as the father of
electricity. Tesla’s alternating current was not triphase, it was diphase. Todays
power grid is the gift of another scientist.
There are numerous other types of
currents like square current, saw current…etc. However these current types are
not or are very rarely used in daily life. More than 30 years i have been
working on electricity amateurishly and i saw square current (sometimes
mentioned as modified sinus or modified alternating corrent) only in cheap ups
and inverters. It is much easier to produce square current from dc than it is
to real ac. So cheaper ups and inverters prefer square current. Other than that
i have not seen or used any other type other than ac and dc since then.
